Shingled magnetic recording (SMR) is a new paradigm in magnetic recording which has the potential to push hard disk drive (HDD) storage capacities above current levels. The most enticing feature of SMR is that it does not require revolutionary developments in media and head design/fabrication like other magnetic storage alternatives such as heat assisted magnetic recording (HAMR) or bit-patterned media. In principle, the existing perpendicular magnetic recording (PMR) heads and media can be used in SMR and provide two digit percentage increases (10 to 20 percent) of areal density capability.
For the purpose of developing new heads/media and assessing their SMR performance, testing on commercial spin stands needs to account for the sequential nature of shingled track writing. In PMR tests which involve off-track writing (for example, squeeze, signal to noise ratio (SNR), error margin (EM), and the like) the track of interest generally does not shift radially with respect to its original location because the off-track writing is done on both sides of the central track and at equal radial distances with respect to the track center. In contrast, in SMR, the off-track writing occurs only on one side of each track, which causes the resulting shingled tracks to change their radial location. This change in radial location creates challenges for measuring certain metrics of performance for magnetic media.